Jakarta: An Indonesian plane carrying 27 people crashed into the sea during a downpour on Saturday in eastern Indonesia, killing everyone on board, a navy officer told local radio.

"I can confirm that all the passengers were killed when the plane exploded as it crashed into the sea," a navy officer involved in the search told ElShinta radio. "The aircraft was smashed to pieces... We found 15 bodies floating on the water and the other passengers are trapped inside the wreckage."

The navy official said about 10 navy divers had tried to locate other passengers inside the wreckage, located at about six kilometres deep.

"We had difficulties locating them due to strong currents and limited equipment," he said adding that the accident took place about 400 metres from the coastline.

Heavy rains poured down when the accident happened around midday, he said.

"We're still checking on the passengers' situation," said Bambang Ervan, a spokesman for the transport ministry. "We also don't know what caused the accident, but the weather was pretty bad at the time."

The airline officials were unable to give comments over the chronology of the accident or an official number of passengers.

Indonesian media, quoting airport officials, said the plane, a MA60 made by China's AVIC International, had crashed 500 metres short of the runway.

The vast Indonesian archipelago relies heavily on air transport and has one of Asia's worst air safety records.

In 2007, a now-defunct Adam Air plane with 102 passengers and crew crashed in deep water off the coast of Sulawesi, with no survivors. No bodies were recovered and only fragments of the aircraft were washed up.

The European Commission, which had barred all Indonesian airlines from its airspace, lifted a ban in 2009 on Indonesian flag carrier Garuda Indonesia after it improved safety standards.